A strain gauge, or gage, is a device for measuring dimensional change primarily on the surface of a specimen as the latter is subjected to mechanical, thermal, or a combination of both stresses. One type of strain gauge is attached to the specimen surface and amplifies mechanically the surface distortion so that the change can be measured on an indicator.
In measuring biological fluids flows, Whitney (1953) first introduced mercury-in-rubber strain gauge plethysmography for the measurement of changes in tissue volume occurring in response to venous occlusion. In use, this strain gauge was placed under tension around the limb under investigation. While effective, this strain gauge is environmentally harmful as it contains mercury, leading to disposal problems.
It is an object of the present system to provide a strain gauge for measuring objects capable of a large deformation, while being environmentally safe.